Biomimetic strategy to prepare thermostable polyimide micro/nanofiber assembled aerogels for airborne particles filtration

Abstract

Development of technologies for air filtration and purification is critical to meet the global challenges of threatened human health and accelerated greenhouse effect. Polymer nanofiber-based aerogels (NFAs) were regarded as a potential new filter for particle pollution removal due to their three-dimensional (3D) network and unique porous structures. However, the NFAs displayed poor mechanical properties, which means that creating desirable filter media capable of capturing fine particles effectively and enduringly, while also withstanding high-speed airstream, still remains a major challenge. Herein, a biomimetic and 3D reconstruction method to construct strong and thermostable aerogels as cascade filters by assembling polyimide nano-microfibers into a gradient hierarchical architecture was reported. The resultant gradient hierarchical structure was composed of nano/micron fiber as skeleton and NFAs as separation interface, achieving efficient filtration for PM0.3 (92.68%, 38.7% higher than that of membrane) and low pressure drop (∼24.6% that of membranes) under high-speed airstream. Moreover, the as-prepared could be treated at 250 ℃ for 30 min without sacrificing filtration performance. The preparation of this attractive material paved the way for designing next-generation air filters for industrial dust removal.